A Chinese hospital has denied involvement in the alleged delivery of the world’s first genetically-edited babies and experts worldwide have voiced outrage at such use of the technology.

The push back comes amid claims made online by scientist He Jiankui that twin girls had been born with DNA altered to make them resistant to HIV, a ground-breaking move that could potentially spark huge scientific and ethical dilemmas.

He, a professor at Southern University of Science and Technology in Shenzhen, claims that his lab had been editing embryos’ genetic codes for seven couples undergoing in-vitro fertilization (IVF).

In a video posted to YouTube Monday, the Chinese researcher said that one of the pregnancies had been successful, and that ostensibly healthy twin girls Lulu and Nana had been born “a few weeks ago.”

He claims that he used a tool known as CRISPR-cas9, which can insert or deactivate certain genes. In his YouTube video, He describes the procedure as having “removed the doorway through which HIV enters.”

But the hospital named in He’s ethical approval documents, Shenzhen Harmonicare Women’s and Children’s Hospital, has denied involvement in the procedures.

“We can ensure that the research wasn’t conducted in our hospital nor were the babies born here,” a hospital spokesperson told CNN. The hospital confirmed that two of the doctors named in He’s documents work at the hospital, and suggested that an internal investigation was underway.

The Shenzhen Health and Family Planning Commission denounced the legitimacy of the hospital ethics committee and the review process that approved the application. It confirmed an investigation was launched Monday to “verify the authenticity of the ethical review of the research reported by media.”

He’s University, Southern University of Science and Technology, said in a statement that the researcher has been on leave since February 1, 2018.

“The research work was carried out outside the school by Associate Professor He Jiankui. He did not report to the school or the department of biology. The university and the biology department are not aware of it,” the institution said, adding that “the Academic Committee of the Department of Biology believes that it seriously violates academic ethics and academic norms.”

He’s claims have neither been independently verified nor peer-reviewed. But if true, the procedure would raise significant ethical questions around gene-editing and so-called “designer” babies.

Editing the genes of embryos intended for pregnancy is banned in many counties, including the US. In the UK editing of embryos may be permitted for research purposes with strict regulatory approval. It is unknown whether the procedure is safe or, if used in pregnancy, whether it can have unintended consequences for the babies later in life, or for future generations.

A ‘huge blow’ to Chinese research

A joint statement has been issued by more than 120 Chinese scientists on the Chinese social media site Wiebo condemning the human genome-editing research.

“The medical ethics review exists in the name only. Directly experimenting on human is nothing but crazy… as soon as a living human is produced, no one could predict what kind of impact it will bring, as the modified inheritable substance will inevitably blend into human genome pool,” they wrote, adding that the trial is a “huge blow” to the reputation of Chinese biomedical research. “It’s extremely unfair to Chinese scientist who are diligent, innovative and defending the bottom line of scientific ethics.”

Julian Savulescu, director of the Oxford Uehiro Centre for Practical Ethics at the University of Oxford, described the alleged births as “genetic Russian Roulette.”

“If true, this experiment is monstrous,” he said. “The embryos were healthy. No known diseases. Gene editing itself is experimental and is still associated with off-target mutations, capable of causing genetic problems early and later in life, including the development of cancer.

“There are many effective ways to prevent HIV in healthy individuals: For example, protected sex. And there are effective treatments if one does contract it,” Savulescu said.

Joyce Harper, a professor in genetics and human embryology at the Institute for Women’s Health, UCL, described the alleged research “premature, dangerous and irresponsible,” calling for public debate and legislation.

“Before this procedure comes anywhere near clinical practice, we need years of work to show that meddling with the genome of the embryo is not going to cause harm to the future person,” she said in a statement.

Yalda Jamshidi, senior lecturer in human genetics, St George’s, University of London pointed out that such controversial research is not necessary for preventing HIV. “We already have ways to prevent HIV infection and available treatments should it occur. We also do not need gene editing to ensure it isn’t passed on to offspring,” she said. “We know very little about the long term effects, and most people would agree that experimentation on humans for an avoidable condition just to improve our knowledge is morally and ethically unacceptable.

Despite ethical concerns in the West, a recent study suggested that the Chinese public is broadly in favor of using gene-editing for medical purposes. An online survey conducted by Sun Yat-Sen University in Guangzhou found that more than two-thirds of the 4,771 people surveyed (575 of whom reportedly have HIV), supported its use in treating diseases, according to the state-run tabloid Global Times.

“(Chinese people) have a high willingness to use of gene in disease prevention and treatment,” Liang Chen, a professor at Sun Yat-Sen University is quoted as saying. “This suggests that the research of gene editing in China not only has a promising potential, but also is responding to the public’s needs.”